In a semiconductor apparatus used in power control equipment or the like, the temperature of a semiconductor device is monitored to prevent breakdown of the semiconductor device due to heating of the semiconductor device under energization. A measurement based on a thermistor, a measurement based on a temperature sense diode, etc. are known as monitoring methods. It is impossible to perform an accurate temperature measurement by the former measurement. An effective area to collector current is small in the latter measurement because a temperature sense diode is mounted on a semiconductor device. Under such circumstances, a technique of calculating the temperature from the temperature characteristic of a collector voltage when constant collector current is applied has been proposed (see PTL 1, for example).